Despite the demonstrated negative effects from tumors and treatments, the health-related quality of life (QOL) of children with brain tumor (BT) has not been well studied. Pediatric BT patients are a particularly challenging group to study because of the relatively small number of patients, diversity of disease, varying functional impact of the tumors, and range of surgical and treatment effects. The current proposal aims to address this issue by validating PROMIS measures (Fatigue, Mobility, Upper Extremity, Depressive Symptoms, Anxiety, and Peer Relationships) in the pediatric BT population. Extending the use of PROMIS measures to the pediatric BT population will provide a useful metric that will enable the evaluation of the usability of the PROMIS domains and instruments in clinical studies. This will make it possible for clinical investigators to monitor the long-term effects of treatment and compare the effectiveness of different treatments, ultimately resulting in improved care for this beleaguered yet under-studied population. We plan to recruit 520 children with brain tumors aged 5-17 and their parents from two existing studies: the Children's Oncology Group phase 2 trial (ACNS1123/ ALTE07C1) and the Proton Collaborative Group Registry study (PCG Registry). Parents of all children will complete the parent-proxy version; patients aged 8-17 (anticipated n=420) will complete the self-reported version of the pediatric PROMIS. Recruitment will follow the protocols of the existing studies but be limited to three years so that the current study can be completed within the allowable project length of this RFA (4 years). We propose the following Specific Aims: Aim 1: To validate pediatric PROMIS measures in children with brain tumors. Specifically, we plan to a) evaluate the psychometric properties of pediatric PROMIS measures used to assess children with brain tumors using item response theory (IRT) models; b) evaluate differential item functioning to ensure comparable item parameters within the brain tumor population compared to the US general population; c) evaluate the validity of pediatric PROMIS instruments using known-groups, convergent and concurrent validity and responsiveness analyses; and d) estimate minimally important clinical differences using clinical anchors with verification by clinicians and health outcome researchers. Aim 2: To enhance the utility of the pediatric PROMIS measures for research and practice. Specifically, we plan to a) compare precision levels of scores obtained from Computerized Adaptive Testing (CAT) versus those from short-forms and their sensitivity to changes over 12 months; and b) link comparable outcome areas between two national efforts of standardization of outcome measures - PROMIS and Quality of Life in Neurological Disorders (Neuro-QOL) Measures.